The thin clients apparently came into vogue after I left the field and went into management. My last 10 years was spent managing Engineers subbed to Sun Microsystems so Solaris was our primary OS.
I bought the two Wyse 5060 thin clients on EBAY and both had 4 GB of memory and a 16 GB SSD with a light version of Windows. I added a second 4 GB DIMM and swapped in a 256MB (my typical overkill) SSD. These are cheaper than a Raspberry Pi at today's prices and will run rings around it CPU wise. All in all a good toy to play with operating systems. They will run Windows 10 and really run well on Linux. I think I paid $40 each for them last year including shipping although they seem to be a little higher these days.
For a really informative guide on mini pcs with upgrade info try the link below. Again, a wealth of information I use often and helped me a lot upgrading my Wyse 5060s.
https://www.parkytowers.me.uk/thin/wyse/5060/